The high reactivity of fluorine is due to A. its high electro negativity B. small size of fluorine atom C. availability of d-orbitals D. strong F – F bond

The correct answer is A. its high electronegativity.

Fluorine is the most electronegative element on the periodic table, which means that it has a strong attraction for electrons. This makes it very reactive, as it is always trying to gain electrons to fill its outer shell.

The other options are not correct.

• Option B, small size of fluorine atom, is not the main reason for its high reactivity. Other elements with small atoms, such as hydrogen, are not as reactive as fluorine.
• Option C, availability of d-orbitals, is not relevant to the reactivity of fluorine. d-orbitals are not involved in bonding in fluorine.
• Option D, strong F – F bond, is not the main reason for the high reactivity of fluorine. The F – F bond is strong, but it is not as strong as the bonds in other halogens, such as Cl – Cl.

In conclusion, the high reactivity of fluorine is due to its high electronegativity.